Dynamic osmotic behavior of chick blood lymphocytes

Abstract

The dynamic response of chick blood lymphocytes to hypotonic shock is investigated using electrical sizing techniques, and an attempt is made to characterize the mechanisms involved. The cells first swell rapidly, as expected, but then gradually return to their initial volume. Maximum volume is attained in 2 minutes and the return is complete within about 15 minutes at room temperature. This cycle is studied under different osmotic strengths, temperatures, and cation compositions; behavior following successive hypotonic and hypertonic shocks is also described. Metabolic inhibitors are shown to have no effect, even at relatively high concentrations, while ouabain (10-3 M) affects only the much slower second-order return process that sets in when the main one is blocked by appropriate external cation concentration.It is proposed that a large increase in membrane permeability to K+ occurs as the cell swells beyond its iso-osmotic volume, but none to Na+. The experimental results are then explained by ascribing the swelling to water entering the cell until the osmotic pressure inside equals that outside, and the return phase to the electrochemical potential gradient for K+ forcing it out of the swollen cell together with the associated anion and water in proportions that preserve osmotic equilibrium. This latter is a non-active process independent of Na+ whose direction can be reversed by using K+ as the cation in the external medium.The existence in the literature of several related observations is pointed out and some of the implications of our findings are discussed briefly in terms of a corrugated membrane structure.

Volume regulation by human lymphocytes: Characterization of the ionic basis for regulatory volume decrease

“…The basic features of lymphocyte behaviour under hypotonic stress were reported for chicken (Doljanski et al, 1974) and human (Ben-Sasson et al, 1975) cells. Using electrical sizing techniques, these authors found RVD to depend on the temperature and the external K+ concentration: and to be insensitive to ouabain and a number of metabolic inhibitors.…”

Volume regulation by human lymphocytes. Identification of differences between the two major lymphocyte subpopulations.

“…Importantly, both passive permeability and active transport of K+ were found to be reduced in B cells as compared with T lymphocytes in isotonic media (18). Although the entire molecular basis of the volumeinduced regulatory pathway is not known, K+ ions were found to play a central role in RVD after hypotonic stress (5,8,19). Thus, it was of interest to determine whether volume regulation is also different (4,5,8) or cell lines (1,20).…”

“…Although the entire molecular basis of the volumeinduced regulatory pathway is not known, K+ ions were found to play a central role in RVD after hypotonic stress (5,8,19). Thus, it was of interest to determine whether volume regulation is also different (4,5,8) or cell lines (1,20). In one study, studies of chronic lymphocytic leukemia cells, which were of B cell origin, were shown to have a slower RVD phase, presumably due to decreased membrane permeability to K+ (4,18).…”

“…When subjected to hypotonic challenge, many cell types have the ability to restore their volume after an initial phase of passive swelling (1)(2)(3)(4)(5)(6)(7)(8)(9). This regulation of cell volume is mediated through shifts in cellular ion and water content (1,3,7).…”

Cell Volume Regulation in Lymphocytes

“…1977;Cheung et al. 1982a;Deutsch et al, 1982;Bui and Wiley, 1981;Doljanski et al, 1974;Ben-Sasson et al, 1975;Lee et al, 1988;Gelfand et al, 1984], whereas lymphocytes of the B cell lineage exhibit minimal RVD [Cheung et al, 1982b;Gelfand et al, 1984], Primary murine peripheral T cells and mu rine T cell clones in a nonproliferating state express low levels of K+ channels McKinnon and Ceredig, 1986;De Coursey et al, 1987] and do not exhibit RVD [Leeetal.. 1988]. However, voltage-gated K+ conductance is increased in these cells during cell cycle progression DeCoursey et al, 1987], enabling these cells to regulate volume in response to hvpotonicity [Lee et al, 1988] (see below).…”